American cleric used more than 60 email accounts to reach followers, including Hasan

The American cleric Anwar al-Awlaki used more than 60 email addresses and sent several thousand emails to his followers, some with encryption and code words, while under FBI surveillance – according to a five-month investigation by Fox News. Some of those emails were exchanged with accused Fort Hood shooter Major Nidal Hasan.

"Fox Files: The Enemy Within," which debuts on the Fox News Channel June 15 at 10 PM ET, draws on exclusive interviews and first hand accounts of the Fort Hood massacre which killed thirteen and injured at least 43 others on November 5, 2009. For the first time, victims of the shooting, as well as senior investigators break their silence about the worst act of terrorism on US soil since 9/11.

"He (Anwar al-Awlaki) was incredibly busy. He – during his peak period – had upwards of sixty email accounts that he was using at any given time," retired FBI agent Keith Slotter told Fox Files.

Slotter, whose career spanned 25 years at the Bureau, was the Special Agent in Charge of the San Diego Field office from 2007-2012. His agents at the Joint Terrorism Task Force (JTTF), which included detailees assigned to the FBI, tracked the cleric who was the public face of Al Qaeda 2.0 and the new digital jihad.

In other words, at times the FBI failed to share key information with intelligence analysts under their supervision.

Slotter, who now works at a private international investigative firm specializing in cyber crime and digital forensics, characterized the number as "...Thousands of emails…over a three year period, tens of thousands."

By 2009, the cleric, the first American on the CIA's kill or capture list, understood he was the target of US and Foreign intelligence services. Fox Files has learned al-Awlaki shunned the use of phones and turned to his keyboard because he believed email communications were more secure.

"He'd let some (emails accounts) go dark, and he'd use ten or fifteen, and then those would go dark, and he'd go to a different set. So he was constantly revolving," Slotter explained. "As you can imagine with that many accounts, it was quite a lot to stay on top of."

Asked how much of it was encrypted or used code words, Slotter replied – "I'll simply say, some was encrypted. And leave it at that. I don’t want to get into the technological aspects."

Slotter has reviewed the emails between al-Awlaki and Major Hasan. The former FBI agent went to them many times after the attack to consider if anything was missed

"I reviewed those emails many times. I had them bound on my desk, had all of them. There was nothing really in there that would indicate al-Awlaki prompting Major Hasan to do something."

Also in 2009, at the same time al-Awlaki was exchanging emails with accused Fort Hood shooter Army Major Nidal Hasan, Fox Files has confirmed the radical American cleric was also sending highly encrypted emails calling for a major terrorist attack.

British court documents obtained and read by Fox Files show Awlaki did use encrypted emails included specific operational instructions to blow up a British plane heading to the United States. Some of them went to Rajib Karim who is now serving thirty years in a British jail.

This exchange was read into the British court record. Here in this exchange from January 2010, Awlaki was clearly interested in Rajib Karim who was a British Airways employee.

Awlaki :

"We search for such men and women. I pray you are one of them, dear brother. I was pleased when your brother conveyed from you Salaams to myself and was excited by hearing of your profession."

"How much access do you have to airports?"

"What information do you have on the limitations and crack in present airport security systems?"

"What procedure would travelers from the newly listed countries have to go through?"

"What ways can you help us based on what you know of your job and our objective?"

"For security reasons, I prefer to communicate with you through your brother's account. However, please maintain the other account by keeping it open just in case I need to contact you there. Awaiting your answer."

While the 19 emails between al-Awlaki and Army Major Nidal Hasan appear much less specific, Senator Susan Collins said the mere contact between an Army officer and a known extremist should have led to more action by federal and military investigators.

"I have read the e-mails and they should have given rise to alarm," Collins said. "Just the fact that a member of our Armed Forces was communicating at all with a radical cleric in Yemen should have given rise to an investigation that was thorough and complete."

Army Staff Sgt. Manning, who was shot six times at Fort Hood, told Fox that he heard Major Hasan scream "allah akbar." Manning spoke exclusively to Fox Files about the massacre. At one point, Manning said he pretended to be dead fearing the shooter would try to finish him off if he appeared only wounded.

"You could lose your security clearance in the Army for having bad credit and be kicked out of the army. But you can't lose your security clearance for talking to uh, a member of Al Qaeda, through e-mail. I mean, it doesn't make any sense."

Catherine Herridge is an award-winning Chief Intelligence correspondent for FOX News Channel (FNC) based in Washington, D.C. She covers intelligence, the Justice Department and the Department of Homeland Security. Herridge joined FNC in 1996 as a London-based correspondent.